We provide quality diffusers. The MacDonald Steel Air Return Diffuser Duct is used where clean filtered air is returned back to the customer’s building to conserve heat/cooling energy and/or to maintain building air pressure.

The ducts are installed at the end of the return air duct and are designed to evenly distribute the air to a larger area, at a lower velocity than that inside the duct system.

This is achieved through a series of holes situated on the topside of the duct, which are sized and spaced to achieve an air exit velocity of approx. 2000 feet per minute, based on a duct system velocity of 4500 feet per minute.

MacDonald Steel Air Return Diffuser Ducts are of 14 gauge welded steel construction, and are available in a range of sizes from 11” diameter up to 26” diameter with or without angle ring flanges.

Diffusers in sizes from 30” diameter to 42” diameter are available equipped with angle ring flanges only and are also equipped with a stiffening angle ring at mid-length.

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Please contact us for more information our diffusers.